Synchronous fluorescence scanning and computer linkages for data analysis have been used to characterize the fluorescent properties, limits of detection, contour maps and 3-dimensional images of a series of aflatoxins, their metabolites, and DNA adducts. The power of these fluorescent techniques has been shown by the demonstration that the number of components within a sample can be delineated using fourth derivative computer analysis of 3-dimensional synchronous fluorescence scanning data. Simple methylation of the 9 position of the guanine residue in AFB1-N7-guanine not only did not increase fluorescence, as has been proposed, but also caused a shift in the optimum delta lambda. Thus, these techniques may provide valuable structural determinations of fluorescent carcinogens and DNA adducts.